When Stephen Wheeler realized he had an aching, swollen finger, he called his primary care doctor, who works for MedStar Health. The doctor referred him to PromptCare, an urgent care clinic in a strip mall in the Baltimore suburbs.

Wheeler says he probably would have ended up waiting a long time if he'd gone to the doctor. And even longer at the emergency room.

But they are all about speedy service here at the urgent care center; Wheeler got in and out in 15 minutes. There's a timer outside of every exam room so the staff knows how long a patient has been waiting. Because Wheeler was already in the system, the clinic was able to pull up his electronic health records and find out if he was allergic to any medications or was due for any other care.

Hospitals already own more than a quarter of the nearly 9,000 urgent care clinics in the U.S. that are drawing patients away from emergency rooms.

"We're still in the very early stages of this trend," says Tom Charland, who runs a consulting company called Merchant Medicine that focuses on walk-in clinics.

He cautions that it's still unclear whether hospitals will actually be successful at managing urgent care centers. Hospitals tend to be good at providing high-quality care, but they're not always so good at customer service.

"Things like understanding how to locate an urgent care clinic in the right retail complex, keeping the wait times down, offering people to book their appointments online — hospitals have yet to prove that they can do that effectively," he says.

But Bob Gilbert, who is in charge of ambulatory services for MedStar, says he's proud of PromptCare's location. He says his company is ready.

"Here we are in a local shopping center where you'd normally not find health care," he says. "People are used to coming here, they know where it is, the parking is free."

The hospital makes money for every patient the clinic refers to a MedStar facility for follow-up care, like a CT scan or an appointment with an orthopedist. Patients who don't yet have a regular source of health care can be referred to a MedStar primary care doctor. But Gilbert says the clinics are also a long-term investment.

And the future is this: Insurers and Medicare are starting to pay providers to keep patients healthy. Providers get a bonus if they manage to lower the cost of the medical services their patients need. These clinics could be a key part of this strategy for hospitals.

The Baltimore location is the first of seven urgent care clinics Gilbert is opening over the next year; MedStar is hoping for 15 in the next few years.

The business of urgent care clinics is booming, with almost 9,000 of them nationwide - you know, when you have a problem that is immediate, but seems not quite worth the emergency room. Most of these urgent care clinics are privately owned. And now hospitals are jumping into the business, even though the clinics don't tend to be big moneymakers. When you find out why, you learn something about the shifting health care industry. Jenny Gold reports.

JENNY GOLD, BYLINE: The PromptCare urgent care clinic sits in a strip mall in the suburbs of Baltimore, squeezed in with a Petco, a deli, and a Party City. It opened in June, replacing a now-defunct Blockbuster. Patients come here for all sorts of basic health issues, from colds and the flu to broken bones and lacerations. Stephen Wheeler came in with an infected finger.

STEPHEN WHEELER: Cutting my nail, I must have cut too far and, you know, got the aching and aching. And I kind of, like, didn't pay it any attention. So when it started swelling up on me, you know, started throbbing, and I'm like, ugh.

GOLD: Wheeler called his primary care doctor, who works for MedStar Health, the same company that owns the urgent care center, along with nine hospitals in the mid-Atlantic.

WHEELER: When I called to schedule an appointment with my doctor, they referred me over here, and I was like, OK, cool. Let me go and see what's, you know, see what's going on.

GOLD: Wheeler says he probably would have ended up waiting a long time if he'd gone to the doctor, and even longer at the emergency room. But they're all about speedy service here at the urgent care center. They even have a timer outside of every exam room so the staff knows how long a patient's been waiting.

WHEELER: The doctor, oh, man, she got me in and out in less than, honestly, 15 minutes.

GOLD: And because Wheeler is already in the system, they were able to pull up his electronic health record and find out if he was allergic to any medications or needed anything else, like a tetanus shot. More than a quarter of U.S. urgent care centers are already owned by hospitals, and Tom Charland says that's just the beginning. Charland runs a consulting company called Merchant Medicine, which focuses on walk-in clinics.

TOM CHARLAND: We're still in the very early stages of this trend. I think we're going to see a lot more hospitals opening urgent care centers, either their first one, or you're going to find hospitals who might have one or two opening more.

GOLD: But he cautions that it's still unclear whether hospitals will actually be successful at managing urgent care centers. They tend to be good at providing high-quality care, but they're not always so good at customer service.

CHARLAND: It's a very consumer-oriented market, with things like understanding how to locate an urgent care center in the right retail complex, keeping the wait times down, offering people to book their appointments online. And hospitals have yet to prove that they can do that effectively.

BOB GILBERT: Here we are in a local shopping center, where you'd normally not find health care. So people are used to coming here. They know where it is. Parking is free.

GOLD: This is the first of seven urgent care clinics he's helping to open over the next year.

GILBERT: What we're trying to do is use these sites, really, to cross-sell MedStar services. So what I want to do is create an environment here that really says get to our door. Come in. If we can't solve your problem here in our facility, we'll help you navigate so your problem can get solved. We'll be a partner in your care.

GOLD: The hospital makes money for every patient the center refers to a MedStar facility for follow-up care, like a CT scan or an appointment with an orthopedist. And patients who don't yet have a regular source of health care can be referred to a MedStar primary care doctor. So that's the plan right now. But Gilbert says the clinics are also a long-term investment.

GILBERT: We're in a place now - we've got sort of the way we do business now and the way we do business in the future. So we're in that gray area. So these urgent care centers, in the future, they're going to be sort of our vehicles for managing the health of populations.

GOLD: Insurers and Medicare are starting to pay providers to keep patients healthy. Providers get a bonus if they manage to lower the cost of the medical care their patients need. And since urgent care centers are such a cheap and convenient way to treat people, if these first ones work out, Gilbert anticipates opening at least 15 in the next few years.

For NPR News, I'm Jenny Gold.

INSKEEP: She's with our partner Kaiser Health News, which is a nonprofit news service. Transcript provided by NPR, Copyright National Public Radio.